linux-ext4 - Re: [PATCH v1] fs/ext4/xattr: check the return value of ext4_xattr_inode_dec

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Message-ID: <Yxxe/X14BiltT352@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
Date:   Sat, 10 Sep 2022 15:25:29 +0530
From:   Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To:     Li Zhong <floridsleeves@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org,
        adilger.kernel@...ger.ca, tytso@....edu
Subject: Re: [PATCH v1] fs/ext4/xattr: check the return value of
 ext4_xattr_inode_dec_ref()

On Thu, Sep 08, 2022 at 09:47:27PM -0700, Li Zhong wrote:
> Check the return value of ext4_xattr_inode_dec_ref(), which could return
> error code and need to be warned.
> 
> Signed-off-by: Li Zhong <floridsleeves@...il.com>
> ---
>  fs/ext4/xattr.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 533216e80fa2..76141ed12bc2 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -1540,7 +1540,9 @@ static int ext4_xattr_inode_lookup_create(handle_t *handle, struct inode *inode,
>  
>  	err = ext4_xattr_inode_write(handle, ea_inode, value, value_len);
>  	if (err) {
> -		ext4_xattr_inode_dec_ref(handle, ea_inode);
> +		err = ext4_xattr_inode_dec_ref(handle, ea_inode);
Hey Li,

My only concern here is in case ext4_xattr_inode_dec_ref() fails, we
overwrite the err value and the actual err from ext4_xattr_inode_write() 
is lost.

I feel the ext4_xattr_inode_write() error code would be more valuable
for the calling function hence that is the one we should propogate.  
Maybe we can just print the warning without overwriting err? 

Regards,
Ojaswin
> +		if (err)
> +			ext4_warning_inode(ea_inode, "cleanup dec ref error %d", err);
>  		iput(ea_inode);
>  		return err;
>  	}
> -- 
> 2.25.1
>